Together, these procedures represent the current standard of care for this patient population. Generally, the SLNB is performed in the same surgical setting as the formal wide excision used to treat the primary tumor. In such cases, the risk for finding sentinel lymph node positivity is somewhere between 8% and 12%, similar to what we find in patients with tumors in the T1b to T2a category. The risk for the presence of microscopic disease in the sentinel lymph nodes is greater in this subgroup of patients with relatively thin melanomas than in most of the remaining patients with stage T1a disease. In addition, we may selectively perform SLNB in patients with category T1a (<0.8 mm) disease if at least 2 or 3 mitotic figures are identified on histologic examination, or if another adverse pathologic sign-such as lymphovascular invasion or an extensively involved deep margin on the biopsy specimen-is present. The overall risk for sentinel lymph node involvement is approximately 20% (ranging from 8% to 55%), and increases as the tumor stage increases in an almost linear fashion. These tumors are classified in the eighth edition American Joint Committee on Cancer (AJCC) melanoma staging system as clinical stage I/II disease, with the tumor stages ranging from T1b to T4b (AJCC stages IB-IIC). The most common indication for SLNB in melanoma is newly diagnosed primary melanoma with a thickness of at least 0.8 mm (rounded up from 0.75 mm) and clinically normal regional lymph node basins. As a result, SLNB-also referred to as “sentinel lymphadenectomy”-was embraced for its role in both therapy and staging. These same studies also demonstrated that the strongest independent predictor of decreased melanoma-specific survival in patients with stage I/II melanoma was sentinel lymph node positivity. It was also determined that treating the disease at a microscopic stage could prevent the development of clinically palpable lymph node metastases (more-advanced stage III disease), which in turn could improve long-term disease control and survival outcomes. Studies performed globally supported the hypothesis that minimally invasive, targeted lymph node biopsy could accurately identify clinically occult (microscopic) regional lymph metastases (early stage III disease). MR It should be stated at the outset that the major motivation for studying the role of sentinel lymph node biopsy (SLNB) in the initial management of newly diagnosed primary melanoma was the need to improve both regional disease control and melanoma-specific survival in patients with regional lymph node metastases. H&O When is sentinel lymph node biopsy indicated in melanoma?
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